Hematologic Neoplasms

December 21, 2015

Incyte has issued results of two phase III studies evaluating Jakafi (ruxolitinib) in patients with Myeloproliferative Neoplasms (MPNs). Data from a five-year follow-up of the COMFORT-II trial, a randomized, open-label study that 53% of patients treated with ruxolitinib (n=78/146) achieved at least a 35% reduction in spleen volume from baseline while on treatment during the study. Additionally, one-third of evaluable JAK2 V617F-positive patients had more than a 20% reduction in allele burden at 3.2 years (38%) and 3.7 years (31%). Patients treated with ruxolitinib also experienced improvements in bone marrow fibrosis (15.8%), with 32.2% reporting stable fibrosis scores. Overall, 59 (40%) and 35 (48%) deaths were reported in the ruxolitinib and best available therapy (BAT) arms, respectively. Median overall survival (OS) was not reached in the ruxolitinib arm and was 4.1 years in the group of patients originally receiving BAT. There was a 33% reduction in risk of death with ruxolitinib (HR, 0.67; 95% CI, 0.44-1.02; P=.06). The estimated probability of survival at five years was 56% with ruxolitinib and 44% with patients originally receiving BAT. The RESPONSE trial was an open-label study evaluating ruxolitinib in patients with polycythemia vera (PV) compared to those with BAT, who had an inadequate response to or had unacceptable side effects from hydroxyurea (HU). The analysis shows that patients who received ruxolitinib had greater mean reductions in white blood cell (WBC) counts compared with BAT or the HU subgroup of the BAT arm, and those reductions were maintained over time. In patients with baseline WBC counts ≥11×109/L, worsening WBC counts were observed in 10.8% of patients in the ruxolitinib arm v. 35.4% in the BAT arm (P=0.0002) and 47.8% in the HU subgroup (P<0.0001). In this same subgroup of patients with elevated WBC counts at baseline, a greater proportion of patients in the ruxolitinib arm (45%) normalized their WBC counts (achieving a WBC ≤10×109/L or a ≥50% reduction from baseline) compared with BAT (22%) or HU (9%) at week 32. The median time to achieve that response with ruxolitinib therapy was eight weeks. 

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